Lessons From The Field: Utility-Scale vs. DG Solar

By NEXTracker on August 1, 2016

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As featured in Solar Industry Magazine

A tracker company offers insight into two very different ground-mounted PV applications.

Ground-mounted solar power arrays are taking root around the world – increasingly displacing traditional fossil fuel power plants with clean, renewable electricity generation. However, system developers and installers face different challenges as they deploy ground-mounted solar in two key – yet distinct – application segments: utility-scale and distributed generation (DG).

Significant differences in utility-scale versus DG may manifest in all phases of a project, from planning and design to logistics and construction. There are variations in process and execution on the technical side (e.g., system design, mechanical, and electrical and civil engineering), as well as on the commercial side (e.g., contracts and procurement). Watch this drone video to witness the difference of these two applications ranging from size to site design and layout.

We’d like to share our experiences and lessons learned from developing solar tracking technologies and installing both types of power systems. In this article, we’ll explore key considerations in the planning and approvals process; system design and layout; labor and project management; installation methods and speed; and grid connection.

Overview

Utility-scale systems typically provide power to many end users via the transmission grid and are often described as being “in front of the meter” – as opposed to DG systems, which are “behind the meter.” Although there is no formal bifurcation of segments by system size, utility-scale systems are typically 10 MW and larger. The aerial photos you see of large expanses of solar panels in the desert represent the archetype for centralized utility-scale solar. The end users for utility-scale power may be in one location or municipality, or they may be distributed across various nodes on a utility’s grid. The direct purchasers of utility-scale power, otherwise known as “off-takers,” often include regulated utilities and municipalities, and dealing with these entities can introduce substantial complexity into contracts.

Meanwhile, DG projects are distinguished from utility-scale projects in that the electricity off-taker and end user are generally the same entity. A DG system may be owned by an individual but is more typically associated with commercial, agricultural or industrial operations where the power is to be used on-site where it’s generated, offsetting electricity costs with clean, reliable solar electric generation. Ground-mounted DG systems typically vary in size up to 10 MW, but there is no formal cutoff.

On the utility-scale side, we’re seeing tremendous sustained growth globally, not only in established markets, but also in emerging ones, such as India and Mexico. With the December 2015 solar investment tax credit (ITC) extension passed by the U.S. Congress, concerns about a serious slowdown in the U.S. utility-scale market have been largely assuaged. We’re also seeing more cases in which utility-scale solar power purchase agreement prices match or even beat those of fossil fuel generation; this is very encouraging and points to nearly limitless long-term growth potential as global demand for energy increases.